γ-TiAl合金高温压缩变形条件下的本构模型

Constitutive Model of γ-TiAl Alloy at Elevated Temperature

采用Gleeble-1500热模拟试验机研究γ-Ti Al合金在1000～1100℃、应变速率在0.01～1s-1的热变形特性,分析了流动应力与热力参数的关系,并建立了γ-TiAl合金在热态变形过程中峰值应力和本构方程模型。结果表明,在试验条件范围内,只有当应变速率为0.01s-1时,才会发生完全动态再结晶;并且,温度分别为1050和1100℃,应变分别达到0.9和0.8时才趋于稳态流变。所建立的数学模型的计算结果与试验数据很好地吻合,从而为制定γ-TiAl合金的锻造工艺提供了理论依据。

The hot compressive deformation behaviors of γ-TiAl alloy were investigated in the temperature range from 1 000 to 1 100 ℃ and at strain rate range from 0.01 s 1 to 1.0 s-1 on Gleeble-1500 hot simulator. The effect of thermomechanical parameters on flow stress was analyzed. A constitutive relationship based on the Zener- Hollomn parameter and Arrhenius equation was proposed for γ-TiAl alloy, and the model of peak stress as a function of temperature and strain rate was also proposed. The result shows that the dynamic recrystallization steadystate of flow stress only appears at the low strain rate, high temperature and strain; the calculation results of the proposed models agree well with the experimental data. Therefore, the proposed model can lay foundation of quality control and process design for the secondary processing of γ-TiAl alloy.